Magnetic core and deflection yoke having the same

Abstract

A deflection yoke includes a bobbin having a cavity formed in the longitudinal direction of the bobbin, and an adjusting coil having a magnetic core on which a thread is cut. The core inserted into the cavity is slidable in the longitudinal direction of the bobbin. The core has a marker formed on only one of ends of the core in the longitudinal direction. The core has been inserted into the cavity from the one end formed with the marker or the other end. The marker is formed on only one of ends of the core before or after the thread is cut thereon.

What is claimed is:  
     
       1. A method of producing a core to be inserted into a bobbin of a deflection yoke, comprising the steps of: 
       forming a marker on a core having the shape of an almost uniform cylinder from a first end to a second end in a longitudinal direction thereof, the marker being formed on only the first end of the core; and  
       cutting a thread on the core while the entire body of the core is transferred between a pair of rollers, one of which is formed with a whetstone in a predetermined direction from the first end formed with the marker or from the second end,  
       wherein the core on which the thread has been cut through the cutting step has a slight difference in diameter between the first end and the second end and the marker formed on only the first end of the core indicates whether the diameter at the first end is slightly larger or smaller than the diameter at the second end.  
     
     
       2. The method according to  claim 1  wherein the marker forming step includes the step of applying ink on only the first end of the core. 
     
     
       3. The method according to  claim 1  wherein the marker forming step includes the step of forming a protrusion or concavity on only the first end of the core. 
     
     
       4. A method of producing a magnetic core to be inserted into a bobbin of a deflection yoke, comprising the steps of: 
       cutting a thread on a core having the shape of an almost uniform cylinder from a first end to a second end in a longitudinal direction thereof while the entire body of the core is being transferred between a pair of rollers, one of which is formed with a whetstone, from the first end or the second end of the core in the longitudinal direction; and  
       forming a marker, after the thread is cut, only on the first end of the core,  
       wherein the core on which the thread has been cut through the cutting step has a slight difference in diameter between the first end and the second end and the marker formed on only the first end of the core indicates whether the diameter at the first end is larger or smaller than the diameter at the second end.  
     
     
       5. The method according to  claim 4  wherein the marker forming step includes the step of applying ink on only the first end of the core. 
     
     
       6. The method according to  claim 4  wherein the marker forming step includes the step of forming a protrusion or concavity on only the first end of the core. 
     
     
       7. A method of producing a plurality of cores to be inserted into a deflection yoke, comprising the steps of: 
       forming a marker on each of the cores, each of cores having the shape of an almost uniform cylinder from a first end to a second end in a longitudinal direction thereof, the marker being formed on only the first end of each of the cores; and  
       cutting a thread on each of the cores while the entire body of each of the cores is transferred between a pair of rollers, one of which is formed with a whetstone, in a predetermined direction from either the first end formed with the marker or from the second end, the predetermined direction being the same for all the cores,  
       wherein each of the cores on which the thread has been cut through the cutting step has a slight difference in diameter between the first end and the second end with the marker formed on only the first end of each of the cores indicates whether the diameter at the first end is slightly larger or smaller than the diameter at the second end.  
     
     
       8. The method according to  claim 7 , wherein the marker forming step includes the step of applying ink on only the first end of each of the cores. 
     
     
       9. The method according to  claim 7 , wherein the marker forming step includes the step of forming a protrusion or a concavity on only the first end of each of the cores. 
     
     
       10. A method of producing a plurality of magnetic cores to be inserted into a deflection yoke, comprising the steps of: 
       cutting a thread on each of the cores, each of the cores having the shape of an almost uniform cylinder from a first end to a second end in a longitudinal direction thereof, while the entire body of each of the cores are successively transferred between a pair of rollers, one of which is formed with a whetstone, from the first or the second end of each of the cores in the longitudinal direction thereof; and  
       forming a marker, after the thread is cut, on each of the cores on only the first end for all the cores,  
       wherein each of the cores on which the thread has been cut through the cutting step has a slight difference in diameter between the first end and the second end with the marker formed on only the first end of each of the cores indicating whether the diameter at the first end is slightly larger or smaller than the diameter at the second end.  
     
     
       11. The method according to  claim 10 , wherein the marker forming step includes the step of applying ink on only the first end of each of the cores. 
     
     
       12. The method according to  claim 10 , wherein the marker forming step includes the step of forming a protrusion or a concavity on only the first end of each of the cores. 
     
     
       13. A method of producing a plurality of deflection yokes comprising the steps of: 
       forming a marker on each of a plurality of magnetic cores, each of said cores having the shape of an almost uniform cylinder from a first end to a second end in a longitudinal direction thereof, the marker being formed on only the first end of each of the cores;  
       cutting a thread on each of the cores while each of the cores in their entirety is transferred between a pair of rollers, one of which is formed with a whetstone, in a predetermined direction starting from either the first end formed with the marker or from the second end, the predetermined direction being the same for all the cores; and  
       inserting the cores, after the thread is cut on each of the cores, into bobbins of the deflection yokes always from the first end formed with the marker that indicates whether the diameter at the first end is larger or smaller than the diameter at the second end due to the thread-cutting or from the second end.  
     
     
       14. The method according to  claim 13 , wherein the marker forming step includes the step of applying ink on only the first end of each of the cores. 
     
     
       15. The method according to  claim 13 , wherein the marker forming step includes the step of forming a protrusion or a concavity on only the first end of each of the cores. 
     
     
       16. A method of producing a plurality of deflection yokes comprising the steps of: 
       cutting a thread on each of a plurality of magnetic cores, each of the cores having the shape of an almost uniform cylinder from a first end thereof to a second end in a longitudinal direction thereof, while the entire cores are successively transferred between a pair of rollers, one of which is formed with a whetstone, from the first or the second end of each of the cores in the longitudinal direction;  
       forming a marker, after the thread is cut, on each of the cores on only the first end for all the cores; and  
       inserting the cores into bobbins of the deflection yokes always from the first end formed with the marker that indicates whether the diameter at the first end is larger or smaller than the diameter at the second end due to the thread-cutting or from the second end.  
     
     
       17. The method according to  claim 16 , wherein the marker forming step includes the step of applying ink on only the first end of each of the cores. 
     
     
       18. The method according to  claim 16 , wherein the marker forming step includes the step of forming a protrusion or a concavity on only the first end of each of the cores.